memcg: fix thresholds with use_hierarchy == 1

We need to check parent's thresholds if parent has use_hierarchy == 1 to
be sure that parent's threshold events will be triggered even if parent
itself is not active (no MEM_CGROUP_EVENTS).

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3eed583895a6..9be3cf8a5da4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3587,9 +3587,13 @@ unlock:
 
 static void mem_cgroup_threshold(struct mem_cgroup *memcg)
 {
-        __mem_cgroup_threshold(memcg, false);
-        if (do_swap_account)
-                __mem_cgroup_threshold(memcg, true);
+        while (memcg) {
+                __mem_cgroup_threshold(memcg, false);
+                if (do_swap_account)
+                        __mem_cgroup_threshold(memcg, true);
+
+                memcg = parent_mem_cgroup(memcg);
+        }
 }
 
 static int compare_thresholds(const void *a, const void *b)